1. The government agency in the United Kingdom that is responsible for internal security and counterintelligence on British territory
   - Security Service [Brit], Military Intelligence Section 5 [Brit]

Type of: international intelligence agency

• decimal point
• decimal system
• decimal system of classification
• decimalisation
• decimalise
• decimalization
• decimalize
• decimate
• decimation
• decimeter
• decimetre
• Decimus Junius Juvenalis
• decipher
• decipherable
• decipherably
• deciphered
• decipherer
• decipherment
• decision
• decision maker
• decision table
• decision-making
• decisive
• decisive factor
• decisively